1. Field of the Invention
The present invention relates to a printing apparatus, such as a copying machine or a printer, and a printing control method, and more particularly to a printing control technique employed by the printing apparatus.
2. Description of the Related Art
In recent years, price reduction of an image forming apparatus (printing apparatus), such as a copying machine or a printer, is under way, and therefore it is desired to reduce the cost of a controller for controlling the operation of the image forming apparatus. For example, when a host-based printer that prints print data received from a host computer is used, printer cost is reduced by transmitting data, which is rasterized by the host computer into a form that can be output by the printer, to the printer for printing.
Further, printers of the above-mentioned type include one which is reduced in size and manufacturing cost by dispensing with a cooling unit, such as a fan. The printer without a cooling unit employs a control method in which a predetermined cooling time period is set when the internal temperature rises such that a printing operation is inhibited from being performed before the internal temperature of the printer falls to a predetermined temperature (this control mode will be hereinafter referred to as “the temperature rise suppression mode”). As a printing control method in the temperature rise suppression mode, there has been proposed, for example, a method in which image data analysis is performed on at least a portion of image data of a print job to thereby determine image density thereof and the temperature of a fixing device as a heating element is controlled based on the determined image density (see Japanese Patent Laid-Open Publication No. 2004-29809).
In the printer without a cooling unit, however, if continuous printing is performed based on a print job, the internal temperature is sometimes increased in a short time, which causes the printer to shift to the temperature rise suppression mode. When the printer shifts to the temperature rise suppression mode, printing operation cannot be restarted until the internal temperature falls to the predetermined temperature, and therefore a user has to wait for a long time before the print job is terminated. Particularly when printing operation is stopped with a few remaining printing sheets, the user finds it inconvenient to use the printer.
However, if the predetermined temperature at which the printing operation is permitted to be restarted is set to a high temperature so as to restart the printing operation earlier, stoppage and restart of printing operation occur frequently. In this case, the user also finds it inconvenient to use the printer, and it cannot be said that the printer is user-friendly.